Physics Unit 4 Electricity and Magnetism (Definations)

Electric Charge

A fundamental property of matter that can be positive or negative, measured in Coulombs.

Electric Field

A region of space in which an electric charge experiences an electrostatic force.

Electric Current

The rate of flow of electric charge.

Ampere

The unit of electric current, equal to a flow of one Coulomb of charge per second.

Potential Difference

The work done per unit charge in moving a positive charge between two points in a circuit.

Volt

The potential difference between two points when one Joule of work is done in moving one Coulomb of charge between those points.

Electromotive Force

The total energy supplied per unit charge by a source around a complete circuit.

Resistance

The opposition offered by a component to the flow of electric current, calculated as potential difference divided by current.

Ohm's Law

The current through a metallic conductor is directly proportional to the potential difference across it, provided temperature and other physical conditions remain constant.

Ohmic Conductor

A conductor that obeys Ohm's Law and displays a linear current-voltage relationship.

Direct Current

An electric current that flows continuously in one direction only.

Alternating Current

An electric current that periodically reverses its direction of flow.

Ideal Ammeter

A meter with zero resistance connected in series to measure current without altering the circuit.

Ideal Voltmeter

A meter with infinite resistance connected in parallel to measure potential difference without drawing current.

Fuse

A safety device containing a short length of wire that melts and breaks the circuit when the current exceeds a predetermined value.

Circuit Breaker

An automatic electromagnetic switch that opens and interrupts a circuit when the current becomes dangerously high.

Magnetic Field

A region of space surrounding a magnet or a current-carrying conductor where a magnetic force can be detected.

Soft Magnetic Material

A material like iron that is easily magnetized and easily demagnetized.

Hard Magnetic Material

A material like steel that is difficult to magnetize but retains its magnetism permanently.

Faraday's Law of Electromagnetic Induction

The magnitude of an induced electromotive force is directly proportional to the rate of change of magnetic flux linkage.

Lenz's Law

The direction of an induced current is always such that its magnetic effects oppose the change causing it.

Transformer

A device used to step up or step down the voltage of an alternating current by electromagnetic induction.